Dual Vaccines Prolong Survival in Metastatic Pancreatic Cancer

The sequential delivery of two vaccines—GVAX and CRS-207—prolonged survival in patients with metastatic pancreatic cancer by about two months, according to the results of a study presented at the 2014 Gastorintestinal Cancers Symposium in San Francisco, California.

Pancreatic cancer is one of the deadliest forms of cancer. Each year, approximately 43,000 people are diagnosed with pancreatic cancer in the United States and close to 37,000 die from the disease. The disease is often diagnosed at an advanced stage, and treatment of advanced disease remains challenging.

GVAX and CRS-201 are two vaccines that stimulate the immune response to pancreatic cancer antigens. GVAX induces a response to a wide variety of tumor-associated antigens, and CRS-207 then boosts the response to mesothelin, which is highly expressed in pancreatic cancer cells.

Researchers from the Johns Hopkins University Sidney Kimmel Comprehensive Cancer Center in Baltimore led a study to test the vaccines in 90 patients. The patients were randomized to receive two doses of GVAX followed by four doses of CRS-207 or to receive six doses of GVAX alone. All of the doses were spaced three weeks apart.

After a median follow-up of 7.8 months, the median survival among those who received the dual-vaccine therapy was 6.1 months, compared to 3.9 months among those who received single-vaccine therapy. What’s more, the one-year probability of survival was 24 percent with dual-vaccine therapy, compared to 12 percent with single-vaccine therapy. Among patients who received at least three doses, dual-vaccine therapy had a greater 5-month overall survival benefit (9.7 months versus 4.6 months).

The efficacy data met the criteria to stop the study early and patients in the single-vaccine arm were able to cross over and receive both vaccines.

The vaccines were well tolerated. Side effects included mild, local reactions, such as erythema, warmth, and swelling after intradermal administration of GVAX, and transient fevers and chills after infusion of CRS-207.

The researchers concluded that dual-vaccine therapy with GVAX and CRS-207 is safe and prolongs survival in previously treated metastatic pancreatic cancer and warrants further study.